The Man Who Saved Tennis

From bad line calls, that is.

Back in the 1990s, Paul Hawkins was a British Ph.D. student in artificial intelligence. He also happened to be a semiprofessional cricket player. He once drove 300 miles to get from his school to a match. Upon arriving at the field, he stepped up to bat and almost immediately fell victim to what he deemed a horrifically bad call by the umpire. "It was a very long drive back to my university after the match ended," says Hawkins, "and I had plenty of time to stew and think."

Most of us react to dumb calls that go against our teams by shrieking at the ref, hurling objects at our TVs, or perhaps posting exasperated rants on Internet message boards. Hawkins did none of these things. Instead, he formulated an idea. What if he could use his technological know-how to make bad calls in sports a thing of the past?

Soon after, in 1999, when he was out of school and working at a high-tech research center, Hawkins set about transforming his dream into reality. He developed a system of high-speed cameras that could track a ball's flight and, in concert with a sophisticated computer program, predict its future path. His first intended application: cricket, of course.

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The bad call that went against Hawkins that fateful day on the cricket pitch had involved an infraction termed "leg before wicket." A cricket bowler (akin to a baseball pitcher) tries to throw the ball past the batsman so that the ball hits the wicket (a little set of wooden stumps stuck into the ground, akin to baseball's strike zone). If the ball hits the batsmen's leg first, it's up to the umpire to guess whether, unimpeded, the ball might have smashed into the wicket or flown right by it. This had always been a subjective call—until Hawkins realized it didn't have to be. Using velocity and trajectory measurements gleaned from the camera system Hawkins had devised, a computer could precisely calculate the probability that the ball's natural path would have brought it into contact with the wicket.

At first, the driving demand for what Hawkins dubbed his "Hawk-Eye" system came from cricket broadcasters, not cricket officials. Instant replays using Hawk-Eye—with overlaid graphics showing the ball's projected path—could instantly settle barstool debates as people watched matches on the telly. "In general," says Hawkins, "we've found that broadcasters, who are in a competitive market, are eager to enhance production and give the viewers better value. Meanwhile, the sports' governing bodies are in a less competitive environment and are more reactive. The broadcasters are a great marketing service for us, though: The governing bodies can see that everyone watching at home knows the correct call and the umpire doesn't." By 2001, Hawk-Eye was appearing as broadcasting tool on televised cricket matches in Britain. Eventually, it became an officiating tool as well.

A technician watches screens with the Hawk-Eye system during the Masters Tennis tournament in London

Photo by Julian Finney/Getty Images.

Adaptation of Hawk-Eye for other sports followed. Repeatedly, Hawkins would offer his system as a means of aiding officials and honoring the sanctity of games, but the sports' ruling organizations would resist. "In all the sports we've done," says Hawkins, "there's been one major catalyzing incident to make the governing body react." In tennis, that incident was a match at the 2004 U.S. Open, pitting Serena Williams against Jennifer Capriati. Several egregiously bad line calls went against Williams, with TV replays (from network high-speed cameras nicknamed "Mac Cams" after John McEnroe) laying bare the chair umpire's errors. A solution was needed. Hawk-Eye provided a few great advantages: 1) It delivered a result much faster than would have been achieved by having a chair ump examine the replays for evidence. 2) It offered a strong sense of finality—you can't argue with a computer. By 2007, Hawk-Eye was being used to settle line-call disputes at Wimbledon and other major tournaments. Now, according to Hawkins, "It's standard at pretty much every single professional tennis event in the world." Though even a system like Hawk-Eye isn't infallible, it can determine to within millimeters whether a ball was in or out, and is sensitive enough that it takes into account nitpicky variables such as the temperature on the surface of a court at match time (which can infinitesimally alter the court's dimensions).

Soccer's moment of truth came in the 2010 World Cup. English player Frank Lampard launched a shot that ricocheted off the bottom of the crossbar, headed straight down, and appeared to hit the ground well past the goal line. The officials missed it, thinking the ball had never entered the goal. Millions of outraged British television viewers voiced their displeasure in the days and weeks that followed. FIFA—soccer's international governing body—had long refused to use technology to aid its referees. But in the wake of the Lampard goal that wasn't, pressure mounted and FIFA reversed itself. This past summer FIFA approved the use of Hawk-Eye (along with a competing system called GoalRef) to determine whether a ball has crossed the goal line or not. A signal will be sent from Hawk-Eye's computer to the referee's watch within one second of any successful goal occurring.

Hawk-Eye was bought by Sony last year for an estimated $32 million, but Hawkins remains the company's director. And he's eyeing new areas in sport from which to remove the human element. Hawkins thinks he could help soccer officials make off-sides calls, and assist baseball umpires in determining whether a runner is safe or out. He's also in serious talks with the NFL about how to improve the league's instant-replay challenge process. He won't disclose exactly what he's working on, but it seems possible that the next time we talk about NFL replacement refs we might be referring to cameras and computers instead of people.